1 /* SPDX-License-Identifier: GPL-2.0 */
2 #ifndef _LINUX_BITOPS_H
3 #define _LINUX_BITOPS_H
4
5 #include <asm/types.h>
6 #include <linux/bits.h>
7 #include <linux/typecheck.h>
8
9 #include <uapi/linux/kernel.h>
10
11 #define BITS_TO_LONGS(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(long))
12 #define BITS_TO_U64(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u64))
13 #define BITS_TO_U32(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(u32))
14 #define BITS_TO_BYTES(nr) __KERNEL_DIV_ROUND_UP(nr, BITS_PER_TYPE(char))
15
16 #define BYTES_TO_BITS(nb) ((nb) * BITS_PER_BYTE)
17
18 extern unsigned int __sw_hweight8(unsigned int w);
19 extern unsigned int __sw_hweight16(unsigned int w);
20 extern unsigned int __sw_hweight32(unsigned int w);
21 extern unsigned long __sw_hweight64(__u64 w);
22
23 /*
24 * Defined here because those may be needed by architecture-specific static
25 * inlines.
26 */
27
28 #include <asm-generic/bitops/generic-non-atomic.h>
29
30 /*
31 * Many architecture-specific non-atomic bitops contain inline asm code and due
32 * to that the compiler can't optimize them to compile-time expressions or
33 * constants. In contrary, generic_*() helpers are defined in pure C and
34 * compilers optimize them just well.
35 * Therefore, to make `unsigned long foo = 0; __set_bit(BAR, &foo)` effectively
36 * equal to `unsigned long foo = BIT(BAR)`, pick the generic C alternative when
37 * the arguments can be resolved at compile time. That expression itself is a
38 * constant and doesn't bring any functional changes to the rest of cases.
39 * The casts to `uintptr_t` are needed to mitigate `-Waddress` warnings when
40 * passing a bitmap from .bss or .data (-> `!!addr` is always true).
41 */
42 #define bitop(op, nr, addr) \
43 ((__builtin_constant_p(nr) && \
44 __builtin_constant_p((uintptr_t)(addr) != (uintptr_t)NULL) && \
45 (uintptr_t)(addr) != (uintptr_t)NULL && \
46 __builtin_constant_p(*(const unsigned long *)(addr))) ? \
47 const##op(nr, addr) : op(nr, addr))
48
49 /*
50 * The following macros are non-atomic versions of their non-underscored
51 * counterparts.
52 */
53 #define __set_bit(nr, addr) bitop(___set_bit, nr, addr)
54 #define __clear_bit(nr, addr) bitop(___clear_bit, nr, addr)
55 #define __change_bit(nr, addr) bitop(___change_bit, nr, addr)
56 #define __test_and_set_bit(nr, addr) bitop(___test_and_set_bit, nr, addr)
57 #define __test_and_clear_bit(nr, addr) bitop(___test_and_clear_bit, nr, addr)
58 #define __test_and_change_bit(nr, addr) bitop(___test_and_change_bit, nr, addr)
59
60 #define test_bit(nr, addr) bitop(_test_bit, nr, addr)
61 #define test_bit_acquire(nr, addr) bitop(_test_bit_acquire, nr, addr)
62
63 /*
64 * Include this here because some architectures need generic_ffs/fls in
65 * scope
66 */
67 #include <asm/bitops.h>
68
69 /* Check that the bitops prototypes are sane */
70 #define __check_bitop_pr(name) \
71 static_assert(__same_type(arch_##name, generic_##name) && \
72 __same_type(const_##name, generic_##name) && \
73 __same_type(_##name, generic_##name))
74
75 __check_bitop_pr(__set_bit);
76 __check_bitop_pr(__clear_bit);
77 __check_bitop_pr(__change_bit);
78 __check_bitop_pr(__test_and_set_bit);
79 __check_bitop_pr(__test_and_clear_bit);
80 __check_bitop_pr(__test_and_change_bit);
81 __check_bitop_pr(test_bit);
82 __check_bitop_pr(test_bit_acquire);
83
84 #undef __check_bitop_pr
85
get_bitmask_order(unsigned int count)86 static inline int get_bitmask_order(unsigned int count)
87 {
88 int order;
89
90 order = fls(count);
91 return order; /* We could be slightly more clever with -1 here... */
92 }
93
hweight_long(unsigned long w)94 static __always_inline unsigned long hweight_long(unsigned long w)
95 {
96 return sizeof(w) == 4 ? hweight32(w) : hweight64((__u64)w);
97 }
98
99 /**
100 * rol64 - rotate a 64-bit value left
101 * @word: value to rotate
102 * @shift: bits to roll
103 */
rol64(__u64 word,unsigned int shift)104 static inline __u64 rol64(__u64 word, unsigned int shift)
105 {
106 return (word << (shift & 63)) | (word >> ((-shift) & 63));
107 }
108
109 /**
110 * ror64 - rotate a 64-bit value right
111 * @word: value to rotate
112 * @shift: bits to roll
113 */
ror64(__u64 word,unsigned int shift)114 static inline __u64 ror64(__u64 word, unsigned int shift)
115 {
116 return (word >> (shift & 63)) | (word << ((-shift) & 63));
117 }
118
119 /**
120 * rol32 - rotate a 32-bit value left
121 * @word: value to rotate
122 * @shift: bits to roll
123 */
rol32(__u32 word,unsigned int shift)124 static inline __u32 rol32(__u32 word, unsigned int shift)
125 {
126 return (word << (shift & 31)) | (word >> ((-shift) & 31));
127 }
128
129 /**
130 * ror32 - rotate a 32-bit value right
131 * @word: value to rotate
132 * @shift: bits to roll
133 */
ror32(__u32 word,unsigned int shift)134 static inline __u32 ror32(__u32 word, unsigned int shift)
135 {
136 return (word >> (shift & 31)) | (word << ((-shift) & 31));
137 }
138
139 /**
140 * rol16 - rotate a 16-bit value left
141 * @word: value to rotate
142 * @shift: bits to roll
143 */
rol16(__u16 word,unsigned int shift)144 static inline __u16 rol16(__u16 word, unsigned int shift)
145 {
146 return (word << (shift & 15)) | (word >> ((-shift) & 15));
147 }
148
149 /**
150 * ror16 - rotate a 16-bit value right
151 * @word: value to rotate
152 * @shift: bits to roll
153 */
ror16(__u16 word,unsigned int shift)154 static inline __u16 ror16(__u16 word, unsigned int shift)
155 {
156 return (word >> (shift & 15)) | (word << ((-shift) & 15));
157 }
158
159 /**
160 * rol8 - rotate an 8-bit value left
161 * @word: value to rotate
162 * @shift: bits to roll
163 */
rol8(__u8 word,unsigned int shift)164 static inline __u8 rol8(__u8 word, unsigned int shift)
165 {
166 return (word << (shift & 7)) | (word >> ((-shift) & 7));
167 }
168
169 /**
170 * ror8 - rotate an 8-bit value right
171 * @word: value to rotate
172 * @shift: bits to roll
173 */
ror8(__u8 word,unsigned int shift)174 static inline __u8 ror8(__u8 word, unsigned int shift)
175 {
176 return (word >> (shift & 7)) | (word << ((-shift) & 7));
177 }
178
179 /**
180 * sign_extend32 - sign extend a 32-bit value using specified bit as sign-bit
181 * @value: value to sign extend
182 * @index: 0 based bit index (0<=index<32) to sign bit
183 *
184 * This is safe to use for 16- and 8-bit types as well.
185 */
sign_extend32(__u32 value,int index)186 static __always_inline __s32 sign_extend32(__u32 value, int index)
187 {
188 __u8 shift = 31 - index;
189 return (__s32)(value << shift) >> shift;
190 }
191
192 /**
193 * sign_extend64 - sign extend a 64-bit value using specified bit as sign-bit
194 * @value: value to sign extend
195 * @index: 0 based bit index (0<=index<64) to sign bit
196 */
sign_extend64(__u64 value,int index)197 static __always_inline __s64 sign_extend64(__u64 value, int index)
198 {
199 __u8 shift = 63 - index;
200 return (__s64)(value << shift) >> shift;
201 }
202
fls_long(unsigned long l)203 static inline unsigned int fls_long(unsigned long l)
204 {
205 if (sizeof(l) == 4)
206 return fls(l);
207 return fls64(l);
208 }
209
get_count_order(unsigned int count)210 static inline int get_count_order(unsigned int count)
211 {
212 if (count == 0)
213 return -1;
214
215 return fls(--count);
216 }
217
218 /**
219 * get_count_order_long - get order after rounding @l up to power of 2
220 * @l: parameter
221 *
222 * it is same as get_count_order() but with long type parameter
223 */
get_count_order_long(unsigned long l)224 static inline int get_count_order_long(unsigned long l)
225 {
226 if (l == 0UL)
227 return -1;
228 return (int)fls_long(--l);
229 }
230
231 /**
232 * parity8 - get the parity of an u8 value
233 * @value: the value to be examined
234 *
235 * Determine the parity of the u8 argument.
236 *
237 * Returns:
238 * 0 for even parity, 1 for odd parity
239 *
240 * Note: This function informs you about the current parity. Example to bail
241 * out when parity is odd:
242 *
243 * if (parity8(val) == 1)
244 * return -EBADMSG;
245 *
246 * If you need to calculate a parity bit, you need to draw the conclusion from
247 * this result yourself. Example to enforce odd parity, parity bit is bit 7:
248 *
249 * if (parity8(val) == 0)
250 * val ^= BIT(7);
251 */
parity8(u8 val)252 static inline int parity8(u8 val)
253 {
254 /*
255 * One explanation of this algorithm:
256 * https://funloop.org/codex/problem/parity/README.html
257 */
258 val ^= val >> 4;
259 return (0x6996 >> (val & 0xf)) & 1;
260 }
261
262 /**
263 * __ffs64 - find first set bit in a 64 bit word
264 * @word: The 64 bit word
265 *
266 * On 64 bit arches this is a synonym for __ffs
267 * The result is not defined if no bits are set, so check that @word
268 * is non-zero before calling this.
269 */
__ffs64(u64 word)270 static inline unsigned int __ffs64(u64 word)
271 {
272 #if BITS_PER_LONG == 32
273 if (((u32)word) == 0UL)
274 return __ffs((u32)(word >> 32)) + 32;
275 #elif BITS_PER_LONG != 64
276 #error BITS_PER_LONG not 32 or 64
277 #endif
278 return __ffs((unsigned long)word);
279 }
280
281 /**
282 * fns - find N'th set bit in a word
283 * @word: The word to search
284 * @n: Bit to find
285 */
fns(unsigned long word,unsigned int n)286 static inline unsigned int fns(unsigned long word, unsigned int n)
287 {
288 while (word && n--)
289 word &= word - 1;
290
291 return word ? __ffs(word) : BITS_PER_LONG;
292 }
293
294 /**
295 * assign_bit - Assign value to a bit in memory
296 * @nr: the bit to set
297 * @addr: the address to start counting from
298 * @value: the value to assign
299 */
300 #define assign_bit(nr, addr, value) \
301 ((value) ? set_bit((nr), (addr)) : clear_bit((nr), (addr)))
302
303 #define __assign_bit(nr, addr, value) \
304 ((value) ? __set_bit((nr), (addr)) : __clear_bit((nr), (addr)))
305
306 /**
307 * __ptr_set_bit - Set bit in a pointer's value
308 * @nr: the bit to set
309 * @addr: the address of the pointer variable
310 *
311 * Example:
312 * void *p = foo();
313 * __ptr_set_bit(bit, &p);
314 */
315 #define __ptr_set_bit(nr, addr) \
316 ({ \
317 typecheck_pointer(*(addr)); \
318 __set_bit(nr, (unsigned long *)(addr)); \
319 })
320
321 /**
322 * __ptr_clear_bit - Clear bit in a pointer's value
323 * @nr: the bit to clear
324 * @addr: the address of the pointer variable
325 *
326 * Example:
327 * void *p = foo();
328 * __ptr_clear_bit(bit, &p);
329 */
330 #define __ptr_clear_bit(nr, addr) \
331 ({ \
332 typecheck_pointer(*(addr)); \
333 __clear_bit(nr, (unsigned long *)(addr)); \
334 })
335
336 /**
337 * __ptr_test_bit - Test bit in a pointer's value
338 * @nr: the bit to test
339 * @addr: the address of the pointer variable
340 *
341 * Example:
342 * void *p = foo();
343 * if (__ptr_test_bit(bit, &p)) {
344 * ...
345 * } else {
346 * ...
347 * }
348 */
349 #define __ptr_test_bit(nr, addr) \
350 ({ \
351 typecheck_pointer(*(addr)); \
352 test_bit(nr, (unsigned long *)(addr)); \
353 })
354
355 #ifdef __KERNEL__
356
357 #ifndef set_mask_bits
358 #define set_mask_bits(ptr, mask, bits) \
359 ({ \
360 const typeof(*(ptr)) mask__ = (mask), bits__ = (bits); \
361 typeof(*(ptr)) old__, new__; \
362 \
363 old__ = READ_ONCE(*(ptr)); \
364 do { \
365 new__ = (old__ & ~mask__) | bits__; \
366 } while (!try_cmpxchg(ptr, &old__, new__)); \
367 \
368 old__; \
369 })
370 #endif
371
372 #ifndef bit_clear_unless
373 #define bit_clear_unless(ptr, clear, test) \
374 ({ \
375 const typeof(*(ptr)) clear__ = (clear), test__ = (test);\
376 typeof(*(ptr)) old__, new__; \
377 \
378 old__ = READ_ONCE(*(ptr)); \
379 do { \
380 if (old__ & test__) \
381 break; \
382 new__ = old__ & ~clear__; \
383 } while (!try_cmpxchg(ptr, &old__, new__)); \
384 \
385 !(old__ & test__); \
386 })
387 #endif
388
389 #endif /* __KERNEL__ */
390 #endif
391